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  1. #1
    Cadet
    Join Date
    Sep 2005
    Location
    Massachusetts
    Posts
    2

    Default Winterizing a Merc 90 hp 4-stroke

    I'm tired of spending $200+ at my marina to have my engine (90hp Merc 4-stroke) winterized. Can anyone tell me what the proper procedure is for winterizing a 4-stroke ? I used to do my old 70hp oil injection Yamaha but I am not sure if there are additional steps for doing a 4-stroke.

  2. #2
    Supreme Mariner Silvertip's Avatar
    Join Date
    Sep 2003
    Location
    Midwest
    Posts
    25,770

    Default Re: Winterizing a Merc 90 hp 4-stroke

    Change lower unit lub and engine oil. If its carbureted, treat the fuel system and fog the the engine just like you did the two-stroke. If its EFI, you should check the owners manual but treating the fuel system with stabilizer such as SeaFoam and again fogging the engine should be all that's necessry. Put her to bed. No antifreeze is necessary as the engine is self draining if stored vertically.

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